US Airways, Heinz and Dell are among well-known brands that this year announced plans to no longer trade as independent companies, shrinking the stock market.

Written by

Matt Krantz
| USA Today

As the market hits new highs, there is a new hurdle to throw at investors: The stock market is shrinking.

The number of companies in which individual investors can buy shares is in a breathtaking decline, continuing a fall that's been years in the making but that's accelerated this year with its record-breaking start to takeovers, mergers and buyouts.